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Fog Type Climatology for South Central Texas

Updated: Aug 31, 2021

Slide 2:

The observation for the “Fog Type Climatology for South Central Texas” focusing on San Antonio. Fog is defined when the temperature and dew point are at the same value through cooling of the air or by adding enough moisture to raise the dew point. Your Dew point is the temperature in which a parcel must be cooled to become saturated.

In the San Antonio Area there were seven main fogs observed.

Slide 3:

Advection Fog – Which is defined as moist air moving over a Colder surface and thus bringing the near- surface air to below its dew point temperature. This can include Warm and Cold Advection Where when Cold air is coming from the North over a moist location or Warm Moist air moving in from the South; for example, the Gulf.

Radiation Fog- Which happens after a warm day, clear night and moisture is present; winds must also be under 5mph.

Frontal Fog- Occurs mainly when warm and cold air masses are mixed, are near saturation and have light winds. This fog type also includes Pre and Post fog which occurs Before and After a frontal system due to rain falling into cold stable air this raising your dew point.

Tropical Disturbance- Which is rare and was only recorded five times over the ten-year time span due to Storms occurring off the coast changing the environment and enhancing conditions to produce fog.

Slide 4:

Visibility varies with each fog type, but the more moisture at the surface the greater the density. Once you remove the Moisture source and or heat from the air the Stratus and Fog clouds will begin to dissipate and visibility will begin to increase.

Slide 5:

Here we have Fog with Snow on Dec 7th 2017 due to a Frontal System and a Dense Fog due to a Radiational Fog on Feb 3rd 2019 which was not a part of the results but was a picture I captured personally here in San Antonio.

Slide 6:

During the time of analysis, the main data acquisition used were with the NCEI (National Center for Environmental Information), the WPC Surface Analysis from NOAA (National Oceanic and Atmospheric Administration) for the whole United States and the Observation Weather Maps from NOAA for the same time period. Together the Fog dates, times and types were recorded from 2008-2018 for San Antonio TX.

Slide 7:

After all the Data was acquired charts were made to show the overall occurrences of Fog in San Antonio, Tx for the seven types of Fog.

· Radiation

· Advection – Warm and Cold

· Frontal -Pre and Post

· Tropical Disturbances

Frontal and Advection were the overall Highest with Frontal having occurred over 259x over the 10 years and Advection occurring 195x.

Slide 8:

Looking at the Annual Frequency over a 12-month timespan for San Antonio, one can see the peak fog occurs were in March with a dips in June. Out of the possible 3,650 potential fog occurrences in San Antonio, it was proven that there was 882.

I believe that after completing the Fog Climatology for San Antonio, those who work for local Emergency Management could benefit from this research to help reduce the risk of fog like accidents which occurred 2,430x in Texas alone in 2016 resulting in 45 casualties according to the Texas Department of Transportation and thus provide better Forecasts of Fog occurrence. NOAA may also be a contributor for the information to have all the documentation as a one stop source for the localized area to have for research purposes.

From here I would like to continue my findings to see how El Niño and La Niña could possibly affect the types and trends of the seven different fog types that occur in the San Antonio area during the 10-year time span.


•Blevins, B. (N.D.). Central texas fog [photograph found in central texas]. Retrieved march 29, 2019, from http://blevinsphotography.Blogspot.Com/2011/10/ (originally photographed 2011, october 29)

•B. (N.D.). Ice fog in minnesota [photograph found in minnesota]. Retrieved march 29, 2019, from http://www.Minnpics.Com/2013/03/ice-fog-in-minnesota.Html (originally photographed 2013, march 25)

•Center, S. P. (2001, january 01). Noaas NWS storm prediction center forecast tools. Retrieved march 18, 2019, from https://www.Spc.Noaa.Gov/obswx/maps/

•Dense fog [personal photograph taken in JBSA LACKLAND]. (2019, february 3).

•Noaa. (2013, November 16). WPC Surface Analysis Archive. Retrieved March 30, 2019, from

•Snow fog [personal photograph taken in JBSA LACKLAND]. (2017, december 7).

•Steam fog [personal photograph taken in jbsalackland]. (2018, november 16).

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